US2572308A

US2572308A - Orifice shoe for well pipes

Info

Publication number: US2572308A
Application number: US43296A
Authority: US
Inventors: Cicero C Brown
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-08-09
Filing date: 1948-08-09
Publication date: 1951-10-23
Anticipated expiration: 1968-10-23

Description

Oct. 23, 1951 C. C. BROWN r ORIFICE SHOE FOR WELL PIPES Filed Aug. 9, 1948 C. C. Brown INVENTOR.

A r roma-y Patented Oct. 23, 1951 UNITED STATES PATENT OFFlCE ORIFICE SHOE FOR WELL PIPES Cicero C. Brown, Houston, Tex.

Application August 9, 1948, Serial No. 43,296

6 Clams.

This invention relates to shoes for well pipes and particularly to shoes for use on pipes which are to be cemented in a well bore.

In conventional methods of cementing pipe strings in a well, the pipe to be cemented is normally provided at its lower end with a device, commonly termed a "float shoe" in the cementing, art. A conventional float shoe generally comprises a hollow body rounded at its lower end to form a guide for the lower end of the pipe and having one or more fluid passageways through the wall thereof for the discharge of cement or other fluid from the bore of the pipe into the annular space between the pipe and the well bore. A back-pressure check valve of conventional design -is ordinarily installed in the bore of the shoe to prevent return flow of cement or other fluid from the annular space into the interior of the pipe.

Well bores in which a pipe is to be cemented will normally be filled with drilling mud or other fluid and when a pipe string fltted with a conventional shoe is inserted in the well bore, the check valve will prevent entrance of such fluid into the interior of the pipe string and will render the pipe buoyant in the fluid, hence the term "float shoe. The pipe string must, therefore, be loaded with other fluid to overcome this buoyancy to permit the pipe string to sink into the well bore and to balance the external fluid pressure to prevent Collapse of the pipe. This operation necessarily involves delay and added operations to effectively snk the pipe string into the well bore. Also, the loading fluid may often be of different character than the fluid initially present in the well and when displaced into the well bore during the course of the cementing Operations, may have deleterious eflects upon the wall of the well bore, particularly in open hole cementing, which may adversely affect the character of the bond subsequently formed between the cement and the wall of the well bore. Still another serious objection to the use of conventional float shoes arises from the piston efect produced on the fluids in the well bore when a pipe, having its lower end closed by such a shoe, is lowered in the well. The close clearances ordinarily provided between the inserted pipe and the well bore, or intermediate pipe string, and the usually viscous nature of the mud fluids in the well are generally responsible for producing this effect which, particularly in the case of long strings of pipe, may' result in the exertion of great pressures on the fluid trapped below the conventional float shoe. s Un- (CI. ISS- 1) 2 der the pressures thus developed, the viscous mud fluids may be forced so deeply into the pores and crevices of the surrounding formations, particularly those from which oil or gas production is sought, as to entirely or partially plug these formations to an extent such that when the pressure is eventually relieved, the oil or gas cannot escape into the well and may result in failure of the well to produce successfully.` y

The present invention has for its principal object the provision of a shoe for well pipes having a novel form of flexible crifice therein through which fluid present in the well bore is admitted at a regulated rate into the pipe string to fill the stringas the pipe is lowered into the well.

An important object is the provision of a pipe shoe having a flexible orifice which will automatically close in response to excessive velocities of fluid flow therethrough.

Other and more specific objects and advantages of this invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings which illustrate a useful embodiment in accordance with this invention.

In the drawings:

Fig. 1 is a longitudinal sectional View of the shoe, showing it connected to the end of a pipe inserted in a well; and

Fig. 2 is an exploded View showing the parts of the shoe in quarter-sectional elevation.

Referring to the drawings, the shoe in accordance with this invention comprises a tubular body o having an internally threaded box ll at one end for connection to a pipe l2. An externally threaded ring !3 having an axial passageway !4 therethrough is adapted to be screwed into the bottom of box H and to seat against an annular shoulder l5 therein. Ring !3 has a cylindrical extension !6 extending into the bore l'! of body I!) below the bottom of box i a fiuid-tight and mechanically strong connecand tapering downwardly to an orifice 24 which. extends axially through the apex of nozzle 20 Nozzle 20 has an l and provides communication between: bore* 723 i and the interier of bore I'I below lip 22. Nozzle 20 is thus provided with flexible walls 25 which taper inwardly and downwardly insrbore -l'|.`

The lower end of body I& is threaded at 25 for the attachment of a housing or cage 21 which is closed at its lower end .and is adapted to encloser'nozzle '2 A=`plu`rality i of' fluid passage'- ways, 281 extend through the walls of cage 21 'to providecommunication between the? exterior and interier 'thereof be -provided-with a plurality of downwardly directed radial flanges 29 which may be sharpened, asat'3-', to formxcutting or millingiteeth forsthelower *end of the cage.

The lower end` of Cage'Z'may Theeabove described device: is empl'oyed in the l following manner: :Che shoe is assembled and connectedr'toi thellowerend oipipe !2, as illustrated-inFig. 1. Thepipe string is then inserted into-a wellbore 3! which willordinarily be filled with .mud fluid. Asthe pipe enters the fluid, the

latteri'flows through 'passageways 28 nd ent r -C.

the' interior ofcage`2'i. The entering fluid will exert pressure against lip 22 due to the resistance' set up by the restricted area of orifice 24, and will expand lip `22'tightly against the wall of bore I 1, threby constraining the fluid to flow through orifice 24 in order 'tol'enter the interior of the pipe 'string." Th rate'at which the fluid will flowbackthrough orice 24 'willnecessarily be determined by its area and the back pressure of th'e fiuid; The restriction formed by orifice 24 will necessarily develop back pressure on the fluid which will be governed largely by the Velocity at which the pipe string is lowered through the fluid; This back pressure will,` of course, be exerted' against the exterior of walls 25 of the ori- Since walls 25 are' fiexible and infice nozzle. wardly tapered, 'as llustrated, when the fluid pressure'thusexerted against the exterior of the Walls exceeds some critical pressure, depending upon the fiexn strength of walls 25, the walls will be caused tocollapse inwardly and will thereby' effectively shut-off bore 23. will'be evident that; if pipe l2 is lowered into Accordingly', it

the' well at an eXcessiVe velocity, the nozzlewalls' will promptly`collapse, shutting off the entrance oftfluid into the pipe and immediately stop further descent oi the pipe. If the rate of descent of :the pipe is then reduced sufiiciently, the natural'resilience of'walls 25 Will cause them to expand and again admit fluid to the interier of the pipepand permit further descent of the pipe into' the l Well.

Itiwill be seen, therefore, that by means of this novel 'form of orifice nozzle, a, pipe string may be lowered .into` a well bore full of fluid at a regulated rate' which permits the pipe to fill up with the' fluid in the well at a controlled rate and which will eliminate the necessity for the loading Operations, heretofore required and which will, at thezsame time, eliminate the pisten efiect on the surrounding earth formations produced by the use of conventional float shoes. At the same time, the pipe string may be lowered into the well at any desired speed, depending largely upon the area of orifice 24, and the collapsing strength of walls 25. The area of orifice 24 will be determined generally in some suitable relation to the area of the pipe string which is calculated to allow the pipe to sink at a desired speed below which the resulting velocity pressure exerted against walls 25 of the nozzle will be less than the collapsing strength of nozzle.

When a pipe equipped with the above-described 'orifice 'shoe has been lowered, as described, to the desired depth in a well, cement or'other fluid' may be forced through the interior of the pipe andpa'ss through nozzle 20 and thence through passageways 28 into the annular space between the pipe and the well bore in the conventional manner. In cementing Operations, the Shoe-in accordance* with this invention may be used with cementing plugs, such as those 'described in my co -pending applications, Serial Nos. 43297 and 46,221, filed August 9, 1948 and August 26,'1948, respectively, which are designed to serve s asee'ctive back-pressure valves to prevent ref-: turn flow`=of cement or otherfluid from the' an- Alter-J- natively,'--the orifice shoe herein described may' nular space to the' interier of' the pipe.

itself serve 'as back-pressure valvej When a body of cement has been displaced' into 'the annular spaeesinthe' conventional' manner, the hydro-' static pr'essure of 'the resulting column of cement; becauseits specic gravity'is normally greater thanthe displacing fluid inside the pipe,'wil1 over-balance that of -the 'column of displacing fluid: inside the pipe and attempt to flow back in-' According to'the pipethrough 'the orifice Shoe. ly, if the pressure on the displacing fluid inside the` pipe' is 'suddenly relieved, as by' pulling 'a va'cuum'on 'the pipe, the resulting sudden backward rush'of cement will develop a velocity pressure exceeding the collapsing strength of nozzle 23 and cause the latter to'shut-ofi, thereby effectivelyblocking the return flow of the cement, and the nozzle Will remain shut-ofi as long as this'excess` pressure is'maintained 'or until the cement has hardened.

It 'will be understood that various changes and alterations may be` made in the details of the illustrativ'e embodiment herein described without departing from the scope of'the appended claims but within the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

1.'A shoe for well pipes, comprising, a generally tubular body adapted to be connected at one end to a well pipe, a generally conical hollow nozzle member constructed of flexible resilient materialaxially disposed in said body with its apex directed toward the opposite end thereof and having the periphery of its base portion in sealing enga gement with the wall of said body, andan axial orifice of restricted area through -the apex of said nozzle member.

2. A Shoe for Well pipes, comprisin'g, a generally tubul'ar body adapted to be connected at one end to a 'well pipe, a generally conical hollow nozzle member constructed of flexible resilient materia1`axially` disposed in' said body with its apex dire'cted toward the opposite end thereof and having the periphery of its base portion in sealing 'engag'ement' with the wall of said body, an axial orifice of'restricted area through the apex-:of said nozzle member, and a perfora'te housing connected to said opposite end of said body and enclosing said nozzle member.

3. A shoe for well pipes, comprising, a generally tubular body adapted to be connected at one end to a well pipe, a generally conicai hollow nozzle member constructed of flexible resilient material axially disposed in said body with its apex directed toward the opposite end thereof, a fiexibe peripheral lip about the base portion of said nozzle member expandible into scaling engagement with the wall of said body, and an axial orice of restricted area through the apex of said nozzle member.

4. A shoe for well pipes, comprising, a generally tubular body, an internally threaded box in one end of said body for connecting said body to a pipe, an externally threaded ring inserted in said box, a generally conical hollow nozzle member disposed in said body having its base portion connected to said ring and in sealing engagement with the wall of said body and having its apex extending toward the opposite end of said body, the walls of said nozzle member being constructed of flexible resilient material, and an axial orice of restricted area through the apex of said nozzle member.

5. A shoe for well pipes, comprising, a generally tubular body, an intemally threaded box in one end of said body for connecting said body to a pipe, an extemally threaded ring inserted in said box, a generally conical hollow nozzle member disposed in said body having its base portion connected to said ring and having its apex extending toward the opposite end of said body, a

flexible peripheral lip about said base portion expandible into sealing engagement with the wall of said body, the walls of' said nozzle member being constructed of 'flexible resilient material, and an axial orice of restricted area through the apex of said nozzle member.

6. A shoe for well pipes, comprising, a generally tubular body, an internally threaded box in one end of said body for connecting said body to a pipe, an externally threaded ring insertible in said box, a generally conical hollow nozzle member having its base portion connected to said ring and having its apex extending toward the opposite end of said body, a flexible peripheral lip about said base portion expandible into sealing engagement with the wall of said body, the walls of said nozzle member being constructed of flexible resilient material, an axial orice of restricted area through the apex of said nozzle member, and a perforate housing connected to said opposite end of said body and enclosing said nozzle member.

CICERO C. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 996,588 Kennedy June 27, 1911 1,810,420 Getty June 16, 1931 2,308,955 Wilson et al Jan. 19, 1943